Gary Speed has been served a harsh lesson in the realities of international management by a man whose longevity is almost unparalleled. Giovanni Trapattoni, 30 years Speed's senior, ensured the Wales manager got off to a wounding start in Dublin. Ireland cantered to victory with a second-half showing which was as impressive as Wales were poor.

From the moment Darron Gibson sent the hosts in front with a terrific long-range shot their victory was never in question. Wales were woefully short of any reply.

For what it is worth, Ireland are the early leaders of the Nations Cup table. Only about 20,000 paying customers turned out to see Ireland win, though, which does not augur well for the future of this competition. Half that number are likely to attend Scotland's meeting with Northern Ireland here on Wednesday night.

Speed has more pressing concerns. "In a funny way, I am glad that happened," he said. "It has emphasised to the players what can happen to them at this level. No one wants to lose like that, especially in their first game. I am disappointed, obviously."

Speed's appointment as the Wales manager at 41 has been widely welcomed in a country which has become accustomed to dismal displays. The small band of supporters who had nipped across the Irish Sea chanted his name with vigour. Speed's next game is against England. Franco Baldini, the England general manager, took in this match with next month's fixture in mind. He and Fabio Capello would have slept soundly.

Ireland almost doused their visitors' optimism within three minutes when Damien Duff's cross-cum-shot scraped the left post of Wayne Hennessey's goal. Wales took 25 minutes to settle, when Hal Robson-Kanu believed he should have had a penalty after being held up by Seamus Coleman. Speed agreed. "Absolutely, it was a penalty," the manager said. "Ireland deserved to win but we should have had a penalty."

A subsequent long-range Simon Church shot almost slipped through the fingers of Shay Given. Those incidents aside, the first half was tame and error-strewn. That would have concerned Trapattoni more than Speed, with Wales – temporarily at least – appearing robust in defence.

Shane Long, a half-time replacement for Kevin Doyle, should have sent Ireland in front five minutes after the interval. The Reading striker, though, blasted over after smart build-up play from Glenn Whelan and Duff.

Such entertainment obviously was not enough for two members of the crowd, who invaded the pitch and jigged around for a minute before burly chaps in luminous jackets had them forcefully removed. Coincidentally, that was the trigger for Ireland to step up a gear.

Duff was next to try his luck, Hennessey blocking his effort after Whelan's latest impressive pass. Gibson, though, decided to leave the Wales goalkeeper with no chance. The Manchester United man scored from 25 yards after playing a one-two with Whelan. Hennessey dived as the ball flew into his top left corner but he need not have bothered.

Welsh hopes of an instant recovery proved in vain. "That has been synonymous with the team over the last few years," said Speed. "When the first goal went in, the heads went down a bit."

Duff got the goal his efforts merited after meeting a cut-back from Jonathan Walters to slam past Hennessey from eight yards. It was the midfielder's first for Ireland for five years. He and Walters were singled out for praise by their manager. That aside, Trapattoni could take heart from competent international debuts by Coleman and Ciaran Clark.

To prove there were at least some thoughts of this fixture having a competitive edge, the first chants of "We're gonna win the cup" emanated from the stands after Duff's strike. Keith Fahey endorsed that sentiment with a curling 20-yard free-kick. As that third goal hit the net, Speed was left with no illusions over the size of his task. Perhaps he sought post-match counsel from Trapattoni.